A new approach to investigating the inflence of prosthetic group structure on heme protein function will be developed by preparing hemoglobin (Hb) and myoglobin (Mb) derivatives in which the heme group has been replaced by a non-porphyrin macrocycle. Specifically, the iron and cobalt complexes of tetrasulfophthalocyanine will be incorporated into apoHb and apoMb using (modified) procedures from the literature, and the functional and structural properties of the products will be analyzed. After conformation of the stoichiometry of binding and purification of products, accurate electronic spectra of reduced and oxidized species will be determined to assist subsequent functional studies. These studies will include oxygen binding measurements, determination of reduction potentials, and measurement of sulfhydryl reactivity. In all cases, potential heterotropic effects will be examined by studying each of the functional properties mentioned above in the presence and absence of organic phosphates and at various values of pH. As all forms of metallophthalocyanine complexes are expected to be low spin, homotropic effects are also of considerable interest; this interest arises from the importance of the spin state change involved in oxygenation of deoxyHb to current models of cooperative interactions in Hb. In additition to homotropic and heterotropic effects, thermodynamic paramaters will be determined for all three types of measurement to assist mechanistic interpretation. It is anticipated that in the long term, these studies will result in the rational design of other water soluble macrocyclic complexes that may be used to probe specific features of macrocycle-apoprotein interaction and the effects of this interaction on holoprotein function.